JPH0335397B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a conductor roll used in a continuous strip surface treatment line.

[Conventional technology]

For conductor rolls used as current-carrying rolls in the electroplating process for strip steel, for example, the smoothness of the roll surface is attracting attention as one of the factors that influences the occurrence of abnormal plating areas called arc spots. Ru. In particular, as a result of recent progress in speeding up production lines, thinning steel strips, and increasing the density of processing current, the roll surface A
A hydroplane phenomenon is likely to occur due to the liquid C such as a plating liquid or a spray liquid existing between the surface B and the steel strip surface B. It is believed that this prevents uniform contact between the roll and the steel strip, reducing the contact area, causing the current density to concentrate locally, and making arc spots more likely to occur. As a countermeasure, it has been proposed to perform group processing on the roll surface to allow the liquid to escape, thereby ensuring uniform contact between the roll and the steel strip and preventing the occurrence of arc spots (Japanese Patent Laid-Open No. 53-43632). ).

It has also been proposed to prevent the occurrence of arc spots by regulating the roll surface roughness within a certain range by buffing, electrical discharge machining, or shot blasting. As a proposal of this kind, for example, PPI (Pears
There are roll rolls with a dull roll surface shape of 150 or more (Japanese Unexamined Patent Publication No. 1985-85696), and there are also roll rolls with a chrome plating on the iron roll surface and a satin finish on the chrome plating surface with shot blasting. (Japanese Unexamined Patent Publication No. 48-97738).

[Problem that the invention seeks to solve]

However, conventionally, in order to define the roll surface roughness within a certain range, the roll surface has been processed by means such as buffing, shot blasting, or electrical discharge machining, which is difficult to precisely control. Therefore, in both cases, the roll surface roughness profile is only irregular, and the maximum height of the roughness is
It was also not possible to strictly control Rmax and 10-point average roughness Rz within arbitrary ranges. Therefore, it is not possible to completely prevent the local concentration of current density by improving the reduction in the contact area between the roll and the steel strip.
There was a problem that the occurrence of arc spots could not be suppressed completely.

This invention was made by focusing on these conventional problems, and uses a high-density energy source to process rolls while accurately controlling the surface roughness within a predetermined range, thereby achieving extremely uniform roughness. The purpose of the present invention is to solve the above problems by providing a conductor roll with a high profile to ensure a sufficient contact area with the steel strip surface.

[Means for solving problems]

This invention achieves the above objects by adjusting the roll surface roughness by using a high-density energy source, (a) center line average roughness Ra is 1.0≦Ra≦4.0 (b) maximum height Rmax is 5.0≦Rmax ≦60.0 (c) The 10-point average roughness Rz is controlled within the range of 4.0≦Rz≦50.0.

[Effect]

When a narrow, sharp beam from a high-density energy source is pulsed and projected onto the roll surface, the metal in the area heated by the beam melts, and the center instantly evaporates into metal vapor, and the vapor pressure The molten metal in the center is blown away and a depression is formed. On the other hand, the blown molten metal re-adheres around the dent, creating a bulge surrounding the periphery of the dent. The depth, diameter, and height of the crater thus formed on the conductor roll surface are determined by controlling the intensity and projection time of the projected high-density energy.

Further, the interval between the craters in the roll circumferential direction is adjusted by controlling the frequency of the projected high-density energy pulse in relation to the roll rotation speed, and the interval between the craters in the roll axial direction is It is possible to arbitrarily set the distribution density of craters by controlling the movement distance of the roll itself or the high-density energy projection device in the roll axis direction. In this way, a large number of craters adjusted to arbitrary sizes are formed on the roll surface at arbitrary pitches and regularly and uniformly distributed. As a result, we adjusted the centerline average roughness Ra, maximum height Rmax, and 10-point average roughness Rz of the roll surface within the optimal range, making the contact between the roll and the steel strip completely uniform and The generation of arc spots on the surface can be effectively prevented.

Note that the center line average roughness Ra is defined by the following formula (1) and Figure 6, and in the figure, the roughness center line is
The direction of the line and vertical magnification is the Y axis, and the measured length is represented by L. In addition, the maximum height Rmax is defined by the following formula (2) and Figure 7, and the 10-point average roughness Rz is defined by the following (3).
It is defined by the formula and FIG. 8, both expressed in microns.

Ra=1/L∫ ^L _O ｜Y｜dL …(1) Rmax=Pmax−Vmin …(2) Rz=(P1+…+P5)−(V1+…+V5)/5…(3) [Example ] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of an embodiment of a conductor roll, in which a chrome-plated coating layer 3 is provided on a surface 2A of a steel pipe body 2 of a conductor roll body 1. surface 3A of
The roll surface 3A (hereinafter simply referred to as the roll surface 3A) is formed into a profile as schematically shown in FIG.

That is, in FIG. 2, 4 is the roll surface 3
A is a relatively deep depression (recess) with an approximately circular opening formed as described later, and 5 is a peripheral wall (protrusion) that rises in a ring shape around the opening of the depression 4; With the convex portion 5, so-called crater-like irregularities (hereinafter simply referred to as craters) 6 are regularly and orderly formed at predetermined intervals, as will be described later.

The crater 6 in this embodiment is formed using, for example, a laser as a high-density energy source. Specifically, the conductor roll main body 1 is rotatably supported and rotated at a predetermined circumferential speed.
Laser pulses from a CO ₂ gas laser device, for example, are projected onto the roll surface 3A as a high-density energy source. Then, the roll surface 3A heated with high energy instantaneously melts and a part of it becomes metal vapor, and the steam pressure generated at this time blows the molten metal on the roll surface 3A around the circumference, forming the depression 4. is formed. At the same time, the blown molten metal adheres to the periphery of the opening of the recess 4 and solidifies, forming a ring-shaped peripheral wall 5. In this way, one crater 6 is formed. Note that the formation of the crater 6 can be performed more efficiently by spraying an auxiliary gas such as oxygen gas at the same time as the laser pulse is projected onto the reaction points on the roll surface 3A.

Depth H1, diameter D, and peripheral wall 5 of the formed depression 4
The height H2 of the bulge and therefore the depth H of the crater are determined by the energy intensity and projection time of the projected laser pulse.

Further, the interval between craters 6 adjacent to each other in the outer circumferential direction of the roll (pitch interval in the outer circumferential direction) is adjusted by controlling the frequency of the laser pulse in relation to the rotational speed of the conductor roll body 1. While controlling in this way, the conductor roll main body 1 is rotated once, and a first row of a predetermined number of craters 6 are formed in a horizontal row at a predetermined pitch interval on the roll surface 3A.

Next, after relatively moving the projection position of the laser pulse onto the roll surface 3A by a predetermined distance in the roll axis direction, the laser pulse is projected in the same manner as in the first row, and a predetermined number of craters 6 in the second row are formed. ing. In this case, the relative movement of the projection position in the roll axis direction may be achieved by sending the laser pulse projection device in the roll axis direction, or conversely by moving the conductor roll body 1 in the roll axis direction. good.

The interval between craters 6 adjacent to each other in the axial direction of the roll (pitch interval P in the roll axial direction) is arbitrarily adjusted by controlling the relative movement distance in the roll axial direction with respect to the contour roll body 1.

In this way, by arbitrarily adjusting the size of each crater 6 and the spacing between each crater in the roll outer circumferential direction and the roll axial direction, the centerline average roughness Ra, maximum height Rmax, and 10-point average roughness can be adjusted. A conductor roll with arbitrarily controlled Rz can be formed.

Therefore, center line average roughness Ra, maximum height Rmax
A plurality of conductor rolls with various 10-point average roughness Rz were manufactured, and the steel strip was electroplated for each roll. The incidence of abnormal plating areas (i.e. arc spots) on the steel strip that occurs during the processing process, as well as the unevenness of the roll surface shape (surface profile) on the soft plating surface of the steel strip to be plated, are The incidence of defects on the plated surface of the steel strip due to transfer was determined for each roll. The results are shown in FIGS. 3 to 5.

In Figure 3, the solid line indicates the occurrence rate of abnormal plating of the steel strip and the center line average roughness Ra of the conductor roll surface.
The chain line represents the relationship between the flaw occurrence rate on the plated surface of the strip steel and the centerline average roughness Ra of the conductor roll surface.

In addition, in Fig. 4, the solid line indicates the occurrence rate of abnormal plating of the steel strip and the maximum height of the conductor roll surface roughness.
The chain line represents the relationship between Rmax and the maximum height of the flaw occurrence rate on the plated surface of the strip steel and the surface roughness of the conductor roll.
It represents the relationship with Rmax.

In addition, in Figure 5, the solid line indicates the occurrence rate of abnormal plating of the steel strip and the 10-point average roughness of the conductor roll surface.
Rz and the chain line shows the flaw occurrence rate on the plated surface of the steel strip and the 10-point average roughness of the conductor roll surface.
It represents the relationship with Rz.

As is clear from Figure 3, the occurrence rate of abnormal plating of steel strip and the average roughness of the conductor roll surface.
Regarding the relationship with Ra, the center line average roughness Ra is
When the thickness is less than 1.0 μm, the occurrence rate of abnormal plating increases rapidly, reaching approximately 0.09% on smooth surfaces.
Abnormal plating was not observed at all within the following range, and the incidence of abnormal plating increased again when the thickness exceeded 4.5 μm. On the other hand, regarding the relationship between the occurrence rate of defects on the plated surface of steel strip and the center line average roughness Ra of the conductor roll surface, no defects were observed on the plated surface when the center line average roughness Ra was 4.0 μm or less. No, but
When Ra exceeds 4.0 μm, the rate of occurrence of defects on the plated surface gradually increases, and for example, when Ra = 5.0 μm, it exceeds 0.2%.

Furthermore, as is clear from Fig. 4, the relationship between the plating abnormality occurrence rate of the strip steel and the maximum height Rmax of the conductor roll surface roughness is
When the value is less than 5 μm, the occurrence rate of abnormal plating increases rapidly, reaching approximately 0.04% on smooth surfaces, and when it is more than 5.0
Abnormal plating is not observed at all in the range of 60.0 μm or less, and the rate of occurrence of abnormal plating increases again when it exceeds 60 μm. On the other hand, the occurrence rate of flaws on the plated surface of steel strip and the maximum height of conductor roll surface roughness
Regarding the relationship with Rmax, the maximum height Rmax is
At 60.0μm or less, no defects are observed on the plated surface, but as the diameter exceeds 60μm, the rate of occurrence of defects on the plated surface gradually increases. For example, at Rmax = 65μm, it is 0.2%.
exceeds.

Furthermore, as is clear from Fig. 5, regarding the relationship between the plating abnormality occurrence rate of steel strip and the 10-point average roughness Rz of the conductor roll surface, the 10-point average roughness Rz is
Below 4μm, the occurrence rate of abnormal plating increases rapidly, reaching approximately 0.025% on smooth surfaces;
No occurrence of abnormal plating was observed in the range of less than 57 μm, and the occurrence rate of abnormal plating increased again when it exceeded 57 μm. On the other hand, regarding the relationship between the occurrence rate of defects on the plated surface of steel strip and the 10-point average roughness Rz of the conductor roll surface, no defects were observed on the plated surface when the 10-point average roughness Rz was 50.0 μm or less. No, but 50μm
When exceeding
For example, when Rmax=65 μm, it reaches 0.58%.

From the above results, in order to prevent the occurrence of arc spots as a plating abnormality on the plated surface of the steel strip, and also to prevent the occurrence of scratches on the plated surface, the surface roughness of the conductor roll should be adjusted ( b) The center line average roughness Ra is 1.0≦Ra≦4.0 (b) The maximum height Rmax is 5.0≦Rmax≦60.0 (c) The height is adjusted so that the 10-point average roughness Rz is within the range of 4.0≦Rz≦50.0. It is preferable to use a density energy source to form the craters while strictly controlling the size of each crater and the spacing between the craters in the roll outer circumferential direction and the roll axial direction.

By regulating the lower limit of the surface roughness of the conductor roll as described above, it is possible to ensure a sufficient contact area between the conductor roll surface and the steel strip surface, thereby preventing the occurrence of arc spots. At the same time, by regulating the upper limit of the surface roughness of the conductor roll as described above, it is possible to completely prevent the risk of causing a large number of defects due to scratches on the soft plated surface of the steel strip surface. It is.

Although we have described the case where a CO ₂ gas laser is used as a high-density energy source, this is not the only option.
Other gas lasers, such as gas lasers, or solid state lasers, such as YAG (yttrium aluminum garnet) lasers, may also be used. In addition to the various lasers described above, other high-density energy sources such as plasma or electron beams may also be used.

Furthermore, conductor rolls with surface roughness regulated within the above range can be processed not only by electroplating treatment, but also by electroplating.
It can also be suitably used as an energizing roll in chemical conversion treatment and heat treatment of steel plates.

〔Effect of the invention〕

As explained above, according to the present invention, the surface roughness of the conductor roll can be adjusted using a high-density energy source such that (a) center line average roughness Ra is 1.0≦Ra≦4.0 (b) maximum height Rmax is 5.0≦Rmax≦60.0 (c) Since the 10-point average roughness Rz was controlled within the range of 4.0≦Rz≦50.0, conventionally, the occurrence rate of roughness on the treated surface of the steel strip, which is the object to be energized, was about 0.01%. It is possible to almost prevent the occurrence of abnormal plating parts called arc spots, and also to prevent the occurrence of flaws on the treated surface of the steel strip.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view illustrating the structure of the conductor roll of the present invention, FIG. 2 is an enlarged sectional view of the portion shown in FIG. 1, and FIGS. Figure 6 is a graph illustrating the correlation between the surface roughness of the conductor roll, the occurrence rate of abnormal plating areas (arc spots) on the surface of the steel strip as an energized object, and the occurrence rate of defects on the plated surface of the steel strip. Figure 7 shows the definition of the center line average roughness Ra, Figure 7 shows the definition of the maximum height Rmax, Figure 8 shows the definition of the 10-point average roughness Rz, and Figure 9 shows the conventional conductor roll. It is an enlarged schematic diagram explaining the contact aspect of the roll surface and the steel strip surface in. 1 is the conductor roll body, 2A is the body surface of the conductor roll, 3 is the chrome-plated coating layer, 3
A is the roll surface.

Claims (1)

[Claims] 1. The roll surface roughness can be adjusted using a high-density energy source such that (a) center line average roughness Ra is 1.0≦Ra≦4.0 (b) maximum height Rmax is 5.0≦Rmax≦60.0 ( c) A conductor roll characterized in that the 10-point average roughness Rz is controlled within the range of 4.0≦Rz≦50.0.